Extrusion apparatus



June 6, 1967 E. s. HANNIS EXTRUSION APPARATUS 5 Sheets-Sweet l Filed Oct. 18, 1965 3,323,l 'Il June 6, 1967 E. s. HANNHS EXTRUSION APPARATUS 5 Sheets-Sh|eet :3

Filed Oct. 18, 1965 I June 6, 1967 E. s. HANMS 3,323,171

EXTRUS ION APPARATUS med oct. 18, 1965 s sheets-sheet s United States rPatent O 3,323,171 EXTRUSION APPARATUS Eugene S. Hannis, Hoboken, NJ., assigner to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Oct. 18, 1965, Ser. No. 497,018 9 Ciaims. (Cl. 18-13) This invention relates to extrusion apparatus and particularly to apparatus for extruding a plastic jacket about elongated articles such as the support wire and the cable core of a self-supporting table.

In the manufacture of self-supporting cable of the type disclosed in Patent 3,207,836 to H. C. Slechta, the extrusion apparatus includes, in addition to a tube for the cable core, a support wire tube which tends to wear due to the abrasive action of the hardened steel wire against the lower internal portion of the tube. The support wire may be a single Wire or it may be comprised of a plurality of strands. When the axial position of the support Wire within the tube shifts downward due to tube wear, the concentricity of the portion of the plastic sheath about the support wire is aifected. Since the support wire contacts the nonsymmetrical bottom portion of the worn tube as it is fed longitudinally therethrough, the sheath thickness will tend to be greater about the upper portion of the Wire than about the bottom portion. In a more extreme case, the wire may wear through the bottom of the tube causing the height of the web portion of the sheath interconnecting the wire and the cable core to be reduced below a predetermined tolerable dimension. Consequently, it has been necessary to replace the tube at intervals to prevent eccentricity in the sheath, and to prevent possible deformation of the web.

At present, repair or replacement of parts -within the extrusion apparatus requires considerable time and effort by a skilled operator. Furthermore, since the extruder crosshead must be dismantled to replace various portions of the apparatus such as the tubes, the cable line may not readily be changed over to produce different sizes of self-supporting cable. The design of more efficient and flexible extrusion apparatus, however, is rendered more diiiicult by the stringent dimensional requirements of selfsupporting cable. The support Wire and cable core must be precisely positioned within a plastic sheath jacket which joins the support wire and cable core by means of an integral connecting web.

Accordingly, an object of this invention is to provide an apparatus for producing self-supporting cable in a more eiicient and economical manner.

Another object of this invention is to provide a new and improved extrusion apparatus for self-supporting cable which may be readily repaired or dismantled for changeover purposes.

A further object of this invention is to provide an extrusion apparatus for self-supporting cable wherein the support wire tube may be readily adjusted to compensate for tube wear.

A more specitic object of this invention is to provide an extrusion apparatus for self-supporting cable which in- -cludes means for adjusting the support wire tube to maintain concentricity of the outer cable sheath and a more ecient design of extruder parts to facilitate assembly and disassembly thereof.

With the above and other objects and advantages in view, an extruding apparatus for extruding plastic about an advancing elongated article comprises a rotatably `mounted tube through which an elongated article is advanced, and means for locking the tube in any one of a series of angular positions to `which the tube is rotated about its axis. The locking means includes a plurality of grooves spaced about the outer periphery of the tube and 3,323,171 *Patented June 6, 1967 l ce a spring-pressed detent insertable into a selected one of the grooves. More particularly, the tube is designed to receive the support wire of a self-supporting cable while a second tube is provided to receive the cable core. The tubes each include circumferential grooves, the grooves being aligned with each other. A pin is insertable between the grooves to maintain the core tubes in position.

In greater detail, the present invention relates to an extrusion apparatus for making self-supporting cable which includes a cable core and a support wire jacketed in a spaced parallel relation within a common protective sheath. The apparatus comprises a cable core tube and a support wire tube each having a corresponding circumferential groove and being xedly positioned Within a tube holder by means of a pin which is inserted between the grooves to force the tubes in opposite directions against the walls of the holder and lock the tubes in a iixed axial position relative to the holder. The support wire tube includes a plurality of concave cam surfaces at spaced intervals about the periphery of the tube designed to be engaged and locked in position by a spring-loaded ball which extends through the holder. This permits rotation of the support Wire tube to compensate -for the abrasive wear caused by the steel support wire, aids in maintaining the concentricity of the sheath which surrounds the cable core and support strand, and extends tube life.

The invention also includes support means mounted within an extrusion chamber, a tube holder having a keyed portion to facilitate `alignment with the support means and a ilange portion extending thereabout to engage in pressure contact a shoulder on the support means and prevent seepage from the plastic ow channel in cooperation with a contoured clamp nut which threadingly en gages the support means and clamps the holder therewithin. A support wire tube and a cable core tube are mounted in a spaced parallel relation within the holder and secured therein by a pin which is forced into an aperture between the tubes formedby corresponding peripheral grooves on each tube. The apparatus also includes a die which forms the sheath about the support wire and cable core as the cable exits from the tubes and forms a connecting web between the wire and cable core.

A more complete understanding of the invention will be had from the following detailed description when read in conjunction with the accompanying drawings, wherein:

FIG. l is a side view in partial cross-section of an extrusion apparatus embodying the principles of the present invention;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1 to illustrate particular features of the invention;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1 to show the cam surfaces of the support wire tube;`

FIG. 4 is an end view showing the tubes mounted with* in the extrusion apparatus with the extrusion die removed;

FIG. 5 is a front View of a typical extrusion die for self-supporting cable; and

FIG. 6 is a side view of a typical self-supporting cable.

Referring now to the drawings, the invention comprises an extrusion apparatus for sheathing self-supporting cable 10 which includes a cable core 11 and a support wire 12 jacketed in a spaced parallel relation within a cornmon plastic sheath 13. During the manufacturing process, the extrusion apparatus forms the plastic sheath 13 concentrically about an advancing core 11 and support wire 12 as they exit from their respective tubes 14 and 15. The plastic material such as polyethylene may be applied about the core 11 and support wire 12 iby a conventional die 16, shown in FIG. 5, or an adjustable die of the type disclosed in the related patent application of E. S. Hannis, Ser. No. 322,178, tiled Nov. 7, 1963 and now Y Patent No. 3,249,965. The die 16 which is mounted within 'tube 15 each include a circumferential groove 26 and '27, respectively, which are positioned opposite each other. A pin 28 is forced transversely to the tubes 14 and 15 into the space between the opposing grooves 26 and 27. The tubes 14 and 15 are thus forced against the walls of the holder 23 to `retain the tubes 14 and 15 therein. The cable core tube 14 and support wire tube 15 may, therefore, be readily removed from the extrusion apparatus by knocking out the pin 28. The ease of replacement is a distinct advantage over prior art designs where the tubes 14 and 15 are force fitted into the holder 23 from the rear and require a time consuming dismantling operation to repair the tubes 14 or 15. Furthermore, the present invention facilitates the changeover to different cable sizes or types -by permitting the rapid interchange of tube holders without a critical alignment procedure.

The support wire tube also includes a plurality of cam surfaces 29 located circumferentially thereabout at fixed intervals. The cam :surfaces 29 cooperate with a spring-loaded ball 31 to retain the support Wire tube 15 in a fixed position within the holder 23. When the lower internal portion 32 of the support wire tube 15 begins to wear excessively due to the weight of the wire 12 traveling along the surface 32, the tube 15 is rotated to the next cam position 29. Thus, the sheath 13 is concentrically applied about the strand 12 with a constant web height since the axial position of the wire remains fixed with respect to the axis of the tube 1S. While the illustrated embodiment shows a plurality of cam surfaces 29 located about the tube 15 only, it may be desirable Vto have a plurality of such surfaces similarly arranged about the cable core tube 14 and operative to compensate for wear caused by the weight of the core passing therethrough.

As shown in FIG. 3, the support wire tube 15 includes a plurality of cam surfaces 29 such as the three surfaces 29 in the illustrated embodiment each of which includes a sloping lead-out portion 33 and a dwell portion 34 for the spring-loaded ball 31. The cam surfaces 29 are designed so that the tube 15 may be readily rotated only in the indicated direction forcing the ball 31 along the sloping portion 33 and into a succeeding cam position. A considerable amount of torque would have to be applied to the support wire tube 15 in order to force the ball 31 out of the dwell portion 34 in the opposite direction. The pressure exerted on the ball 31 by spring 36 may be adjusted by means of the threaded member 37, all three cooperating with each otherto act as a cam engaging means.

The tube holder 23 is readily positioned within the extrusion apparatus by means of the key 38 which enga-ges the slotted portion or recess 39 in the support means or adapter 41. The key 38 is secured to the holder by the set screw 40. This eliminates the difficulty encountered in previous designs in aligning index marks on the mating parts within the slotted portion or recess 39. A flange portion 42 of the holder 23 is pressed against the end portion 43 of the support means or adapter 41 to prevent plastic seepage from the flow channel 21 entering about the cable core 11 and support wire 12 via the slight annular opening between the adaptor 41 and the clamp nut 46, then through the threads mating the adaptor 41 and the clamp nut 46, then through the space between the flange 42 and end portion 43 of adaptor 41, and finally around the rear of holder 23. An internally threaded portion 44 of the clamp nut 46 engages a threaded portion 47 of the adapter 41 to clamp the. tube holder 23 in position. A shoulder 4S on the clamp nut 46 forces the holder 23 against the adapter 41 as the clamp nut 46 is tightened. Thus, the holder design avoids the use of set screws which tend to wear or the problems of shoulder surface tburrs which permit seeepage from the flow channel 21 to pass through the tubes 14 and '15 causing lumps on the plastic :sheath 13. As a further advantage, the contoured frustoconical clamp nut 46 includes a plurality of flat surfaces 49, for example twelve surfaces, which are spaced about the circumference to provide a smooth flow path for the plastic and which can nevertheless be readily gripped by a tool for assembly operations.

The adapter 41 is threadingly engaged with the guider tube 51 and includes a plurality of threaded apertures 52 about its periphery. A corresponding plurality of tapered screws 53 are threaded through the apertures 52 to engage the threaded recesses 54 in the guider tube 51. These screws 53 facilitate the alignment of the adapter 41 with the guider tube 51 in the same relative position during each assembly operation.

It is to be understood that the above-described arrangements are simple illustrative examples of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art, which Will embody the principles of the invention and fall within the spirit and scope thereof. For example, the above arrangement is not limited to self-supporting cable but may be used to apply a plastic sheath about vari-ous types of communications cable.

What is claimed is:

1. An extruding apparatus for extruding plastic material about an advancing elongated article comprising:

a rotatably mounted tube through which an elongated article is advanced and about which the plastic fiows Y onto the advancing article, and

means for locking the tube in any one of a series of angular positions to which the tube may be rotated about its axis.

2. An extruding apparatus according to claim 1 wherein the locking means includes:

a plurality of grooves in the outer periphery of the tube, and

a spring pressed detent insertable into any selected one of the grooves.

3. In an extrusion apparatus for sheathing self-supporting cable having a chamber and an extrusion orifice at the outlet of the chamber:

support means mounted within the extrusion chamber and having a slotted portion at one end thereof,

a tube holder having a key portion to engage the slotted portion of the support means for alignment purposes and having a flange portion extending thereabout to abut against the support means,

a support wire tube having a circumferential groove extending thereabout and a plurality of cam surfaces at predetermined intervals about the circumference,

a cable core tube having a circumferential groove extending thereabout, said tube being positioned with the support wire tube in a spaced parallel relation within the holder with the lrespective circumferential grooves opposite one another,

means mounted in the space between the corresponding grooves to force the tubes against the holder and retain said tubes therewithin,

means mounted within the holder for engaging a cam surface and retain the support Wire tube in a fixed position relative to the cable core tube while permitting indexing of the tube to a succeeding cam surface to compensate for support tube wear, and

clamping means mounted to the support means to retain the holder in the support means and cooperate with the holder to prevent seepage of the sheathing material `about the core and support wire in the extrusion chamber.

4. An extrusion apparatus in accordance with claim 3 wherein the clamping means comprises:

an outer portion including a truste-conical portion and a plurality of at surfaces positioned about the base of the frusto-conical portion to provide a smooth flow path for the extrudate within the extrusion chamber, and

an inner portion deiining an aperture for the tube holder, said inner portion including a shoulder portion to engage the flange portion of the holder and threaded means for mounting the clamping means to the support means.

I5. An extrusion apparatus in accor-dance with claim 3 wherein the cam surface engaging means comprises:

a ball engaging the cam surface,

spring biasing means maintaining the ball in contact with the cam surface, and

adjusting means for regulating the spring pressure on the ball.

6. In an extrusion apparatus for applying a plastic sheath about the Wire core and the support strand of a self-supporting cable and a connecting web therebetween, said apparatus having an extrusion chamber therein, the combination comprising:

a die mounted at the outlet of the extrusion chamber for regulating the llow of plastic material about the cable core and support wire,

a first elongated tube located Within the chamber and extending to the chamber outlet, said tube guiding the support wire longitudinally through the chamber to cooperate with the die in forming a sheath about the Wire and being rotatable about its axis to a predetermined number of xed positions,

a second elongated tube located within the chamber and extending to the chamber outlet in a spaced parallel relationship with the iirst tube, said tube guiding the cable core longitudinally through the chamber to cooperate with the die in forming a sheath about the cable core and with the first tube and die in forming a connecting web between the sheaths, and

support means for retaining the first and second elongated tubes within the extrusion chamber, said means including a holder having an aperture to receive the tubes, means for forcing the tubes transversely against the Walls of the aperture to anchor the tubes therein and means for engaging the holder to lock the holder within the extrusion chamber.

7. An apparatus in accordance with claim 6 wherein:

the lirst elongated tube for the support wire includes a plurality of grooves located about its circumference to permit rotation of the tube to a predetermined number of fixed cam positions, and

the holder includes cam engaging means mounted therethrough to cooperate with the grooves in determining the rotation of the tube for the purpose of maintaining sheath concentricity.

8. An apparatus in accordance with claim 6 wherein the holder includes:

a key portion for aligning the holder with reference to the holder engaging means, and

a flange portion extending circumferentially thereabout to prevent plastic seepage about the core and support wire in cooperation with the holder engaging means.

9. An apparatus in accordance with claim 6 wherein the holder engaging means includes:

apertured support means xedly mounted Within the extrusion chamber to receive one end of the holder therein, and

apertured clamping means positioned about the holder and engaging the support means to retain the holder in position.

References Cited UNITED STATES PATENTS 2,105,812 1/1938 Gordon et al.

2,766,480 10/1956` Henning 18-13 X 3,074,107 l/l963 Mase et al. 18-13 FOREIGN PATENTS 574,615 4/1959 Canada.

WILLIAM I. STEPHENSON, Primary Examiner. 

1. AN EXTRUDING APPARATUS FOR EXTRUDING PLASTIC MATERIAL ABOUT AN ADVANCING ELONGATED ARTICLE COMRISING: A ROTATABLY MOUNTED TUBE THROUGH WHICH AN ELONGATED ARTICLE IS ADVANCED AND ABOUT WHICH THE PLASTIC FLOWS ONTO THE ADVANCING ARTICLE, AND MEANS FOR LOCKING THE TUBE IN ANY ONE OF A SERIES OF ANGULAR POSITIONS TO WHICH THE TUBE MAY BE ROTATED ABOUT ITS AXIS. 